'null' reference error in StreamStorageConfig excludeOutputs

[theastrowolfe]

excludeOutputs is not initialized in the StreamStorageConfig.

https://github.com/opensensorhub/osh-core/blob/master/sensorhub-core/src/main/java/org/sensorhub/impl/persistence/StreamStorageConfig.java#L37

I have a fix locally. I'll open a PR with this momentarily.